This invention relates to dental syringes for injecting warm water and air into the mouth of a dental patient and atomizing the water with the air.
In the dentistry profession it is often necessary while treating a patient to clear the work area within the patient's mouth of waste material utilizing a syringe which produces a controlled spray of pressurized water or air, or both simultaneously such that the air atomizes the water. A conventional syringe for performing the aforementioned function comprises a body, or head, having a handle attached at the bottom thereof and an elongate tip attached to the head for insertion into the oral cavity of the patient to guide the water and air therein. In some cases such a syringe is designed only to provide either water or air, but not both, and in such cases there ordinarily is a single button on the top of the body for actuating the stream of fluid. Syringes providing both water and air ordinarily include two separate buttons adjacent one another on top of the body which may be pressed alternatively either to actuate the water or the air, or they may be pressed simultaneously to actuate both fluids and produce atomization of the water. A flexible supply conduit attached at one end to the head for conducting the fluids thereto is attached at its other end to a source of warm water and air.
A tip for a conventional syringe which supplies both water and air utilizes a multiple-piece metal assembly which is soldered together. Such an assembly typically comprises a large pipe and a small pipe concentrically disposed within the larger pipe, an exit manifold attached to both pipes at the patient end of the tip and a combination entry manifold and collet member attached to the pipes at the head end of the tip such that the two manifolds hold the pipes in position relative to one another thereby permitting water to flow through the center pipe and air through the passage between the center and the outer pipe. The exit manifold is typically provided with several outer, air exit holes disposed around a center, water exit hole and a 45-degree front chamfer which places the air holes behind the water hole so that the air may expand and strike the water as soon as it exits for effective atomization. Also, the tip assembly is bent a slight, predetermined amount for ease of access to the work area within the oral cavity.
The conventional tip assembly is attached to the syringe head by placing it through a nut which threads into the head and tightens on the collet; consequently, the nut must be completely unscrewed to remove the tip. Additional drawbacks of such a conventional tip are that due to the labor and materials involved in manufacturing such a metal tip it must be sterilized and reused as it is too expensive economically to discard, and the metal of which it is made prevents it from being reshaped without impairing its proper functioning as a guide for the water and air.
The pushbuttons mounted on a conventional syringe head for controlling the fluid emitted by the syringe typically comprise multiple-piece assemblies having a button body, a button stem, a snap ring, a diaphram and a valve mechanism. Such pushbutton assemblies must be removed with the aid of a screwdriver or a special tool and the use of many separate parts tends to increase the cost of production and the difficulty of repair.
The water and air supplied by a conventional syringe are heated at their source to avoid discomfort to the patient. In dual syringes the supply conduit utilizes two adjacent tubes attached to the source, one for carrying water and the other for carrying air. Of course, where a single function syringe is utilized only one tube is needed. The tubes are attached through the handle of the syringe to the body by barbed nipples which are permanently attached to the body, at least in the case of dual syringes. A major drawback of this heating arrangement is that the fluids in the conduit cool off between uses which causes a delay between the time that the syringe is actuated to produce an immediate spray and the arrival of warm fluids, thereby resulting in the initial injection of cold fluids into the oral cavity of the patient which produces considerable discomfort.